The following commit has been merged into the x86/urgent branch of tip:

Commit-ID: 527f721478bce3f49b513a733bacd19d6f34b08c Gitweb: https://git.kernel.org/tip/527f721478bce3f49b513a733bacd19d6f34b08c Author: Babu Moger babu.moger@amd.com AuthorDate: Fri, 20 Aug 2021 16:52:42 -05:00 Committer: Borislav Petkov bp@suse.de CommitterDate: Sun, 22 Aug 2021 09:11:29 +02:00

x86/resctrl: Fix a maybe-uninitialized build warning treated as error

The recent commit

064855a69003 ("x86/resctrl: Fix default monitoring groups reporting")

caused a RHEL build failure with an uninitialized variable warning treated as an error because it removed the default case snippet.

The RHEL Makefile uses '-Werror=maybe-uninitialized' to force possibly uninitialized variable warnings to be treated as errors. This is also reported by smatch via the 0day robot.

The error from the RHEL build is:

arch/x86/kernel/cpu/resctrl/monitor.c: In function ‘__mon_event_count’: arch/x86/kernel/cpu/resctrl/monitor.c:261:12: error: ‘m’ may be used uninitialized in this function [-Werror=maybe-uninitialized] m->chunks += chunks; ^~

The upstream Makefile does not build using '-Werror=maybe-uninitialized'. So, the problem is not seen there. Fix the problem by putting back the default case snippet.

[ bp: note that there's nothing wrong with the code and other compilers do not trigger this warning - this is being done just so the RHEL compiler is happy. ]

Fixes: 064855a69003 ("x86/resctrl: Fix default monitoring groups reporting") Reported-by: Terry Bowman Terry.Bowman@amd.com Reported-by: kernel test robot lkp@intel.com Signed-off-by: Babu Moger babu.moger@amd.com Signed-off-by: Borislav Petkov bp@suse.de Reviewed-by: Reinette Chatre reinette.chatre@intel.com Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/162949631908.23903.17090272726012848523.stgit@bmog... --- arch/x86/kernel/cpu/resctrl/monitor.c | 6 ++++++ 1 file changed, 6 insertions(+)

diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c index 57e4bb6..8caf871 100644 --- a/arch/x86/kernel/cpu/resctrl/monitor.c +++ b/arch/x86/kernel/cpu/resctrl/monitor.c @@ -304,6 +304,12 @@ static u64 __mon_event_count(u32 rmid, struct rmid_read *rr) case QOS_L3_MBM_LOCAL_EVENT_ID: m = &rr->d->mbm_local[rmid]; break; + default: + /* + * Code would never reach here because an invalid + * event id would fail the __rmid_read. + */ + return RMID_VAL_ERROR; }

if (rr->first) {